Evaluation of zinc and copper levels in vaginal tissues and whole blood: correlation with age

Abstract

Background: Zinc and copper are essential trace elements and play a crucial role in the homeostasis of connective tissues. In this study, we aimed to define zinc and copper levels in the vaginal tissue and establish whether a correlation exists between the zinc and copper levels either or both in whole blood or vaginal tissue samples and whether the finding correlates with the age of the patient or at least with her menopausal status.

Methods: We collected whole blood and vaginal tissue samples from 32 women and measured their zinc and copper levels by inductively coupled plasma optical emission spectrometry. We have performed Student's t test to evaluate the differences in the mean levels of trace elements and multiple regression to evaluate the association between vaginal tissue zinc/copper levels and age, menopausal status, number of vaginal deliveries, and zinc/copper blood levels.

Results: Zinc levels were significantly higher in both the vaginal tissues and whole blood samples than copper levels (p < 0.01). In the vaginal tissue samples, a strong positive correlation could be detected between zinc and copper levels (r = 0.82, p < 0.01). In the vaginal tissue, a negative correlation was found for zinc and copper levels with the age of women (r = - 0.27, p = 0.04 and r = - 0.56, p < 0.01). Multiple linear regression model (age, menopausal status, vaginal delivery and copper/zinc blood levels) showed that only age remained a significant predictor for zinc and copper vaginal tissues levels (p = 0.03, 95% CI - 2.28 to - 0.06; p = 0.004, 95% CI - 1.76 to - 0.34).

Conclusions: Zinc and copper levels in the vaginal tissue decline with age. Out of the examined variables (age, menopausal status, vaginal delivery, and copper/zinc levels), only age is a significant predictor of vaginal zinc/copper levels.

Keywords: Ageing; Copper; ICP-OES; Vagina; Whole blood; Zinc.

Fig. 1

Correlation analysis of zinc and copper levels in the vagina. a Correlation between vaginal tissue zinc (Zn) and copper (Cu) levels (mg/kg). A significant strong positive correlation could be detected between zinc and copper vaginal tissue levels (r = 0.82, p < 0.01). b Correlation between vaginal tissue zinc (Zn) levels (mg/kg) and the age (years) of women. A significant negative correlation was found between zinc levels and the age of women (r = − 0.27, p = 0.04). c Correlation between vaginal tissue copper (Cu) levels (mg/kg) and the age (years) of women. A significant negative correlation was found between copper levels and the age of women (r = − 0.56, p < 0.01)